A few things:

• The "lightbulb" cartel was to ensure uniformity over consumer bulbs. 1000 hours was chosen as the best compromise between lifetime and brightness. There were still 10k bulbs made and sold by members of the "cartel". You could still buy long-lasting stuff. Also and as an aside, it's always funny to me that the only proof anyone can offer of planned obsolescence is an industry cartel that hasn't existed since before WW2. Literally nothing else.

• Apple solders the ram directly to the board because it's cheaper. Connectors are expensive. We do the same at my company. It probably saves several dollars per connector. And well, Apple customers just don't enough about it to buy something else that's upgradeable. I know that's not the satisfying answer but that's certainly it: consumers don't care enough to buy upgradeable models from elsewhere.

• As also mentioned elsewhere, I doubt they can get the same thinness with the RAM slots put in. Thinness seems to be what their consumers want, so they are naturally going to focus on that.

>Also, companies that restrict your ability to repair a product is planned obsolescence.

The idea behind that isn't to make it fail faster or sell more. The purpose behind it is because counterfeiting is a huge problem, especially for Apple. There's literally an entire shadow industry that buys broken iphones, puts generic parts in them to make them work again, then resell them, and then when those break because they aren't repaired properly, the people who bought them take them to Apple for repair, which costs them money.

This isn't just for computers: tractors, industrial equipment, aircraft parts, etc are very easy to forge and have some factory somewhere in China make a substandard version for it for less than half the cost. Fake aircraft parts were implicated in some plane crashes in the 90s until regulators clamped down on it.

I'm sure there's a revenue component to the service subscription aspect as well, but again, people aren't willing to buy other stuff over it, so clearly it's not important enough to buyers to go elsewhere.

Again, not a satisfying answer, but that's a large component of it.